Nunit.Framework.Internal.Test's Fixture property is null from inside ITestBuilder

[amine-aboufirass]

As a follow up to a previous issue I have been trying to implement a custom attribute using the ITestBuilder interface as follows:

[AttributeUsage(AttributeTargets.Method)]
   internal class TestBuilderAttribute : Attribute, ITestBuilder
   {
      public IEnumerable<TestMethod> BuildFrom(IMethodInfo method, NUnit.Framework.Internal.Test suite)
      {
         throw new NotImplementedException();
      }
   }

I decorated a test case as follows:

[TestFixture]
   public class MyTestFixture
   {
      [SetUp]
      public void SetUp()
      {
         ...
      }

      [TestBuilder]
      [Test]
      public void MyTest1()
      {
         ...
      }

      [TestBuilder]
      [Test]
      public void MyTest2()
      {
         ...
      }

      public void PrintHello()
      {
         Console.WriteLine("hello world");
      }

I would like to access PrintHello such that it gets triggered before each test. Unfortunately, from inside the BuildFrom() method in ITestBuilder, suite.Fixture is null, so I cannot downcast it as indicated in the previous issue.

Am I doing something wrong here? Why is suite.Fixture null-valued even though I clearly have a fixture?

[stevenaw]

Would ICommandWrapper work for you? There is a derived IWrapSetUpTeardown marker interface you can implement to inject code to run in the SetUp/Teardown phase.

https://docs.nunit.org/articles/nunit/extending-nunit/ICommandWrapper-Interface.html

The docs suggest using MaxTimeAttribute as a simple, minimal example to reference: https://github.com/nunit/nunit/blob/master/src/NUnitFramework/framework/Attributes/MaxTimeAttribute.cs

[stevenaw]

Oh sorry I see now a bit more from the original issue. It's difficult to know without seeing the code you have which isn't working. Are you able to share a bit of what you have tried to implement in your custom attribute?

[manfred-brands]

@amine-aboufirass The suite passed in to the BuildFrom method is the Fixture you are in and the property ClassName is its type. Note that you cannot call a non-static method as at the time the ITestBuilder is run, it is to create tests, not to run them and the class will not be instantiated.

I'm still confused what you are trying to do and why you cannot call your PrintHello from the [SetUp] method.

@stevenaw Indeed the derived ICommandWrapper allows you to wrap tests, but the needed class TestCommand is in the Internal namespace so I don't know if that is really meant to be used by outside code?

[stevenaw]

@manfred-brands Huh, you are quite right, the callbacks passed in there are for a TestExecutionContext in the internal namespace. I'm surprised as we also recommend ICommandWrapper as an extension point in https://docs.nunit.org/articles/nunit/extending-nunit/Custom-Attributes.html, which would require an implementer of a custom command to receive a TestExecutionContext in the constructor as well as to extend one of the Commands in the internal namespace. This seems a bit contradictory.

There's a bit of a discussion about intent of the types in the internal namespace here #1426, but as far as I can tell it wasn't clear-cut and still requires a more thorough cataloging and decision about the different types in the (sub)namespaces.

I think you are right, it would help to know a bit more about what @amine-aboufirass is trying to do.

[OsirisTerje]

This is more about usage, so moving it to Q&A discussions.